Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B49/00—Arrangement or mounting of control or safety devices
  • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D11/00—Self-contained movable devices, e.g. domestic refrigerators
  • F25D11/003—Transport containers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/08—Refrigeration machines, plants and systems having means for detecting the concentration of a refrigerant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/12—Inflammable refrigerants
  • F25B2400/121—Inflammable refrigerants using R1234
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/13—Economisers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2500/00—Problems to be solved
  • F25B2500/19—Calculation of parameters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2600/00—Control issues
  • F25B2600/11—Fan speed control
  • F25B2600/112—Fan speed control of evaporator fans
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2600/00—Control issues
  • F25B2600/25—Control of valves
  • F25B2600/2513—Expansion valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/19—Pressures
  • F25B2700/193—Pressures of the compressor
  • F25B2700/1931—Discharge pressures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/19—Pressures
  • F25B2700/193—Pressures of the compressor
  • F25B2700/1933—Suction pressures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/19—Pressures
  • F25B2700/197—Pressures of the evaporator
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/21—Temperatures
  • F25B2700/2115—Temperatures of a compressor or the drive means therefor
  • F25B2700/21151—Temperatures of a compressor or the drive means therefor at the suction side of the compressor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/21—Temperatures
  • F25B2700/2117—Temperatures of an evaporator
  • F25B2700/21175—Temperatures of an evaporator of the refrigerant at the outlet of the evaporator
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D11/00—Self-contained movable devices, e.g. domestic refrigerators
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
  • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B40/00—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

Definitions

• the invention relates to a method of determining a refrigerant or a composition of refrigerants in a refrigeration system comprising an expansion valve, an evaporator, one or more evaporator fans, a condenser one or more condenser fans one or more temperature sensors, one or more pressure sensors, a compressor, and a controller for controlling the refrigeration system, the controller comprising a memory, the expansion valve, the evaporator and the compressor being fluidly interconnected in a refrigerant path having refrigerant flowing therein.
• the invention also relates to a controller for controlling a refrigeration system, the controller comprising a memory, the refrigeration system comprising an expansion valve, an evaporator, one or more evaporator fans, a condenser, one or more condenser fans one or more temperature sensors, one or more pressure sensors, a compressor, the expansion valve, the evaporator and the compressor being fluidly interconnected in a refrigerant path having a refrigerant or a composition of refrigerants flowing therein.
• the invention further relates to a cooling machine in a reefer container e.g. in a truck, a railway container, an intermodal container or a shipping container comprising a refrigeration system comprising an expansion valve, an evaporator, one or more evaporator fans, a condenser, one or more condenser fans one or more temperature sensors, one or more pressure sensors, a compressor, and a controller for controlling the refrigeration system, the controller comprising a memory, the expansion valve, the evaporator and the compressor being fluidly interconnected in a refrigerant path having refrigerant flowing therein.
• Cooling systems known as vapour compression systems used for example in refrigeration systems e.g. in a truck, a railway container, an intermodal container or a shipping container are commonly designed as dry-expansion systems.
• the superheat parameter is a value, calculated based on refrigerant properties, pressure, and temperature measurement at pre-defined points in the refrigeration system, typically at an evaporator outlet of the refrigeration system. From measurement of the pressure, a saturated temperature of the refrigerant is calculated at dew-point, by use of equations describing relation between vapour pressure and temperature, such as a known Antoine equation.
• Superheat can be defined as temperature difference between measured temperature at the evaporator outlet and the calculated saturation temperature from the pressure measurement.
• vapour refrigerant cannot reach a superheat below 0° Kelvin, because the temperature remains constant for a given pressure when the refrigerant changes phase between liquid and vapour and vice versa.
• the superheat will be, at minimum, close to 0° K or even negative.
• the refrigerant R1234yf is considered a replacement for refrigerant R134a and has been adopted by the automotive industry despite the difference in safety classification. For other refrigeration systems it is a requirement to maintain the same safety classification as R134a.
• a possible solution is a refrigerant mixture of 44% R134a and 56% R1234yf known as R513A, which fulfils these requirements and has been adapted e.g. in the reefer industry.
• Equation 1 the general formula of the Antoine equation is shown, with which the saturated temperature of the refrigerant T (in °C) can be calculated based on the pressure measurement P (in bar) and refrigerant specific constants a o , a 1 anda 2 .
• a method for calibrating a superheat sensor is known, the superheat sensor being arranged in a refrigeration system comprising an expansion valve, an evaporator and a compressor, the expansion valve, the evaporator, the superheat sensor and the compressor being fluidly interconnected in a refrigerant path having refrigerant flowing therein, the method comprising the steps of: increasing an amount of liquid refrigerant in the evaporator,
• the amount of liquid refrigerant in the evaporator is initially increased. This may, e.g. be done by increasing an opening degree of the expansion valve, by decreasing a rotational speed of the compressor or by decreasing a secondary fluid flow across the evaporator.
• An object of the invention is to determine a composition of refrigerant within a refrigeration system e.g. in a truck, a railway container, an intermodal container or a shipping container.
• step b Adjusting the refrigeration system in relation to the composition determined by step b.
• a composition of refrigerant based on table values of Antoine parameters and compared to values from one or more sensors read out from a test run followed by an adjustment or calibration of the refrigeration system in relation to the composition of refrigerant determined by the result of the test run.
• a calibration point A is determined at a set-point temperature T set A of the refrigeration system, set to 20°C +/-10°C.
• values of T suc A and P Suc A, based on set-point temperature T set A is stored in the memory of the controller.
• a calibration point B is determined at a set-point temperature T set B, set to 0°C +/-10°C.
• values of T suc B and P Suc B, based on set-point temperature T set B is stored in the memory of the controller.
• a calibration point C is determined at a set-point temperature T set C, set to -20°C +/-10°C.
• values of T suc C and P SUc C, based on set-point temperature Tset C is stored in the memory of the controller.
• two calibration points B and C are determined at a selected and fixed specific Antoine parameter a o .
• the method further comprises the steps of:
• the steps of the method are carried out when one or more of following conditions are met:
• the method further comprises readout of a result in a display
• a further object of the invention is to provide a cooling machine in a reefer container e.g. a truck, a railway container, an intermodal container or a shipping container comprising a refrigeration system where the controller is configured to control the method according to one or more of the above embodiments.
• a reefer container e.g. a truck, a railway container, an intermodal container or a shipping container comprising a refrigeration system
• the controller is configured to control the method according to one or more of the above embodiments.
• Figure 1 schematically shows a vapour compression cycle in a refrigeration system
• Figure 2 shows a simplified diagram of an economized vapour compression cycle, as used in reefer containers
• Figure 3 shows a variety of R134a-R1234yf blends, compared to saturation temperature of pure R134a
• Figure 4 illustrates a curve fit of concentration of R134a in R134a-R1234yf mixtures.
• a vapour compression cycle in a refrigeration system 1 is shown in Figure 1 .
• the refrigeration system 1 comprises an expansion valve 2, an evaporator 3, one or more evaporator fans 4, a condenser 5, one or more condenser fans 6, one or more temperature sensors 7, one or more pressure sensors 8, a compressor 9, and a controller 25 for controlling the refrigeration system 1 , the controller 25 comprising a memory 26, the expansion valve 2, the evaporator 3 and the compressor 6 being fluidly interconnected in a refrigerant path 10 having refrigerant flowing therein.
• the controller 25 is connected to controllable components such as expansion valve 2, evaporator fan or fans 4, condenser fan or fans 6, and compressor 9, in the refrigeration system 1 in order to be controlled by the controller 25.
• the connection can be a wired connection 20, a wireless connection, Bluetooth or a combination thereof.
• FIG. 2 A simplified diagram of an economized vapour compression cycle, as used in reefer containers as shown in Figure 2, where an economizer 1 1 , a further expansion valve 12 and a receiver 13 is incorporated in the refrigerant path 10 between the evaporator 3 and the condenser 5.
• a further pressure sensor 8 is placed between the condenser 5 and the compressor 9.
• the purpose of the economizer 1 1 is to reduce run time of the compressor 9.
• Equation 1 the general formula of the Antoine equation is shown, with which the saturated temperature of the refrigerant T (in °C) can be calculated based on the pressure measurement P (in bar) and the refrigerant specific constants a o , a 1 anda 2 .
• Figure 4 shows an example of a curve fit of concentration of R134a in R134a- R1234yf mixtures for the parameter a o .
• Table 1 shows the parameters a o , a 1 and a 2 for pure R134a and pure R1234yf and mixtures of these.
• Equation 1 The Antoine equation from Equation 1 can be extended with offsets from pressure and temperature sensors 7, 8, as shown in Equation 2
• Equation 2 By rearranging the equation and introducing variables k in Equation 3 and j in Equation 4 it can be seen that calculating the saturated temperature from the measured pressure can be done from three parameters (a o , j and k) as shown in Equation 5.
• a calibration point for each parameter is needed.
• the refrigerant is present in two- phase state, i.e. liquid and vapour refrigerant existing at the same time in the location of temperature and pressure measurement, as this ensures that the measured pressure and temperature correspond to each other.
• Ensuring the refrigerant to be present in two-phase state can be done by opening of the expansion valve more than in normal operation and/or increasing compressor speed and/or decreasing evaporator fan speed.
• the temperature of these calibration points needs to be carefully selected, and depends on the characteristics on pressure transmitter, temperature sensor and refrigerant.
• the temperature of the extended Antoine equation is expressed in °C, so one calibration point may be selected at 0°C.
• This condition can for instance be achieved by defrosting an iced-up evaporator by air (fans are running but defrost heaters and hot gas defrost are inactive).
• a limited period e.g. one minute
• liquid refrigerant from the high-pressure side of the refrigeration system flows into the evaporator and temperature and pressure can be recorded for a period of time.
• the period of time can be from a few seconds to a couple of minutes, for example between 30 seconds and 2 minutes, preferably about 1 minute or for a longer period, for example up to 10 minutes.
• the period of time should be determined to form a known value and long enough to give a sufficient amount of readings (logging).
• Equation 5 simplifies to:
• T offset is minimal.
• the offset of the pressure transmitter is typically expressed in percentage of full scale, which means that the pressure reading becomes more accurate towards high pressure levels and less accurate towards low pressure levels.
• a first calibration point is then selected to be at e.g. 0°C.
• a second calibration point should therefore be selected at a pressure level as high as possible in the refrigeration system, while ensuring refrigerant is present in liquid and vapour state.
• a suitable second calibration point is e.g. +20°C when the refrigeration system has not been operating for some time.
• a limited period e.g. one minute
• liquid refrigerant from the high-pressure side of the refrigeration system flows into the evaporator and temperature and pressure can be recorded for e.g.10 minutes.
• a third calibration point could be selected at lowest possibe temperature achievable with the refrigeration system, e.g. -20°C or -40°C, as the difference between staturation temperature of R134a and R1234yf is at its largest.
• the refrigeration system shall contrail the temperature stable to the lowest possible temperature and increase opening of the expansion valve by 5 - 20% more than required normally for a period of time. This higher opening will ensure, that the compressor is not damaged by returning liquid refrigerant during the calibration period.
• the lowest possible temperature depends on current design of a refrigferation system.
• NIST Refprop version 9.1 the equation of state is applicable to -53.15°C for R1234yf and -103.3°C for R134a.
• the lowest possible temperature shall therefore be found between -53.15°C and -103.3°C. It is obvious that newer research data and/or new versions of NIST Refprop will provide for even lower temperatures.
• default refrigerant parameters is stored in the controller memory 26.
• Refrigerant parameters for the refrigerants R134a, R513A and R1234yf are listed in table 2.
• the saturated temperature can be determined by use of equation
• FIG. 3 An example of a variety of R134a-R1234yf blends, compared to saturation temperature of pure R134a is illustrated in Figure 3, where 100% R134a is represented by a line 30 being horizontal and 100% R1234yf is represented by a line 40 being most inclining and 100% R513A is represented by a line 50 having an inclination being in between A and B.
• R134a represents mixtures of R134a and R1234yf in compositions from 0, 1 :0, 9 to 0,9:0, 1 of the two refrigerants. It should be noted that R513A is a mix of 56% R1234yf and 44% R134a.
• the so computed saturated temperature of the refrigerant can be subtracted from the suction temperature to determine the degree of Superheat (SH), as shown in equation (2).
• the temperature sensor is placed on an outside of a tube. In case the temperature sensor is placed after a bend, then the refrigerant flow is not stratified and exposed all the time to either gaseous or liquid refrigerant. In e.g. a straight line, the flow will be stratified and exposed to either gaseous or liquid refrigerant, subject to operational condition of the unit and flow characteristics in the system.
• the refrigeration system have to be controlled at three distinct operation points:
• Box Temperature is defined as the set-point temperature Tset.
• the controller 25 shall operate the unit to be running stable at first of the calibration points. As stability criteria, different definitions can be applied. Examples can be:
• Difference between the temperature sensor 7, measuring temperature of returning air from cargo to the evaporator 3 and the temperature sensor 7, measuring supplied air from the evaporator 3nto the cargo is between -1 .5 K and + 1.5 K.
• the temperature sensor 7, measuring the returning air from the cargo to the evaporator 3 is within 0.75 K from set- point temperature stored in the controller 25.
• the saturated temperature and suction temperature need to be brought to equality, this is done by ensuring liquid refrigerant is present for a certain amount of time at the location of the temperature sensor 7 Tsuc. Physically, this can be done by excessively increasing the opening degree of the expansion valve 2, to allow more refrigerant to pass through the evaporator 3 than can be evaporated.
• the expansion valve 2 can be an electronic expansion valve.
• speed of the evaporator fan or fans 4, 6 can be reduced to lower an amount of heat (from the air) present at the evaporator 3 to evaporate all liquid refrigerant.
• the refrigeration system 1 needs to operate for a certain, but limited amount of time, to allow for this equalization of temperatures to occur. The time may not be excessively long, as during this process, liquid refrigerant is returned to the compressor 9, which will dilute oil and reduce lubrication between moving parts within the compressor 9, and increase the risk for liquid droplet entering a compression chamber in the compressor 9 and damage discharge reed valves (or con rod), due to the liquid droplets being incompressible.
• Equation (3) Equation (3) reformulated:
• Equation (6) inserted in equation (4):
• c. Set and fix a o to the last known (and confirmed) value of the refrigerant that was filled in production or under qualified service.
• d. Average value of a o from a pair of two refrigerants (R134a & R513A; R134a & R1234yf or R513A & R1234yf), as it could be that operators select to only use two of the three possible refrigerants.
• the Antoine parameters a 1 anda 2 are then determined in the two calibration points and a o is set to a o . fix . (Analog procedure should a 1 ora 2 be fixed).
• a further simplification can be to perform a single calibration, i.e. to fix a o and a 1 and adjusat 2 to the value obtained from the calibration process.
• Table 5 Illustration of preferred storage of calibration parameters in the controller memory 26.
• a method for determining a refrigerant or a composition of refrigerants in a refrigeration system 1 comprising an expansion valve 2, an evaporator 3, one or more evaporator fans 4, a condenser 5, one or more condenser fans 6 one or more temperature sensors 7, one or more pressure sensors 8, a compressor 9, and a controller 25 for controlling the refrigeration system 1 , the controller 25 comprising a memory 26, the expansion valve 2, the evaporator 3 and the compressor 6 being fluidly interconnected in a refrigerant path 10 having refrigerant flowing therein, comprising the steps of: a) Running a test run and read out values from one or more of the sensors 7, 8;
• step b Determining a composition by the result of step a;
• step b Adjusting the refrigeration system 1 in relation to the composition determined by step b.
• This method makes it possible to determine a composition of refrigerant based on table values of Antoine parameters and compared to values from one or more sensors read out from a test run followed by an adjustment or calibration of the refrigeration system 1 in relation to the composition of refrigerant determined by the result of the test run.
• a calibration point A is determined at a set-point temperature T set A, set to 20°C +/-10°C.
• values of T suc A and P suc A, based on set-point temperature Tse t A, is stored in the memory 26 of the controller 25.
• a calibration point B is determined at a set-point temperature T set B, set to 0°C +/-10°C.
• values of T suc B and P suc B, based on set-point temperature Tse t B, is stored in the memory 26 of the controller 25.
• a calibration point C is determined at a set-point temperature T set C, set to -20°C +/-10°C.
• values of T suc C and P SU c C, based on set-point temperature Tset C is stored in the memory 26 of the controller 25.
• two calibration points B and C are determinded at a selected and fixed specific Antoine parameter a o .
• the method further comprises the steps of:
• the steps of the method are carried out when one or more of following conditions are met:
• the method further comprises readout of a result in a display
• a controller 25 for controlling a refrigeration system 1 comprising a memory 26, the refrigeration system 1 comprising an expansion valve 2, an evaporator 3, one or more evaporator fans 4, a condenser 5, one or more condenser fans 6 one or more temperature sensors 7, one or more pressure sensors 8, a compressor 9, the expansion valve 2, the evaporator 3 and the compressor 6 being fluidly interconnected in a refrigerant path 10 having a refrigerant or a composition of refrigerants flowing therein, where the controller 25 is configured to control the method according to one or more of the embodiments of the method.
• a cooling machine in a reefer container e.g. in a truck, a railway container, an intermodal container or a shipping container, comprising a refrigeration system 1 comprising an expansion valve 2, an evaporator 3, one or more evaporator fans 4, a condenser 5, one or more condenser fans 6 one or more temperature sensors 7, one or more pressure sensors 8, a compressor 9, and a controller 25 for controlling the refrigeration system 1 , the controller 25 comprising a memory 26, the expansion valve 2, the evaporator 3 and the compressor 6 being fluidly interconnected in a refrigerant path 10 having refrigerant flowing therein, characterized in that the controller 25 is configured to control the method according to one or more of the embodiments of the method.

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• Engineering & Computer Science (AREA)
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• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Devices That Are Associated With Refrigeration Equipment (AREA)

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• 2019
  • 2019-01-15 DK DKPA201970027A patent/DK181305B1/en active IP Right Grant
• 2020
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